If you've ever shot it or even let it roll around loose in a hip quiver..ITS DULL!
I either replace the blades on muzzy/thunderhead style heads (I've tried to resharpen them...possible...but a pain in the rump to deal with those thin little things!)

For you guys that are nervous about a "new" head flying true I think of it this way: Razorsharp blade two inches off is likely to be just as good as a dull one that's spot-on. Soo, you can use a almost sharp blade and know you're giving up an edge (no pun) or you can use a "new" blade and take a chance of being in the same position you would've been in.

My opinion anyways...do what you're comfortable with.